One very important ligaments is coraco-acromial ligament

One very important ligaments is coraco-acromial ligament
Moves the head of the humerus and the biggest bulge in the humerus under this link
So it is natural that there is in that place the bag under this link subacromial bursa
If flame in this bag, shoulder movement will be painful and very limited
Under the bag there tendon above the spinal supraspinatous tendon, which also could be harmed and cause pain and lack of movement in the shoulder

That the true strength of the shoulder does not come from the bones or ligaments in the shoulder, but: four short muscles that surround the joint and that attach themselves to the bone humerus from the front and the top and back.

These muscles are:
Muscle under the scapula subscapularis muscle.
Above the muscle (above the fork scapula) supraspinatus muscle
Spinal muscle infraspinatus muscle
Short muscle teres minor muscle
This muscle is called: rotator cuff (in English: Rotator cuff)

Per muscle work but all the muscles working to prove the shoulder joint
These muscles if his vice Vsttih the joint to move freely large